Getting Started with MaNGA
We have highlighted a few things that you should keep in mind when Working with MaNGA Data. Please familiarize yourself with that page as it can be critical to the science you do with the data. Beyond that, the fastest way to familiarize yourself with the MaNGA data is to follow along with our MaNGA tutorials. Below, we supplement those tutorials with a few pointers to get you started working with MaNGA data!
Selecting/Finding a galaxy with MaNGA observations
The two main catalogs with observational metadata and global galaxy properties for MaNGA are the DRPall file and the Targeting Catalog file. You can directly access the fits files containing these catalogs via the SAS or you can use the CAS to run SQL queries; see the tutorials here and here .
If you're interested in whether or not your galaxy of interest has been observed by MaNGA, you can cross reference the galaxy's coordinates with the DRPall file, find more details here. Please consult the description of the DRPall file here. You can also use the DRPall catalog to select a galaxy sample based on global properties from the NASA-Sloan Atlas, find more details here.
If you're interested in whether or not your galaxy of interest may be observed by the MaNGA survey in the future, you can cross reference the galaxy's coordinates with the Targeting Catalog. This will tell you if your galaxy is in the parent sample of galaxies that can be targeted by MaNGA. If the galaxy has not been observed, you can use the MaNGA field layout forecast (specifically using the fits file linked to in that page) to get an idea of the likelihood that the galaxy will be observed.
Note:In these catalogs, each galaxy has a unique MaNGA-ID, but a galaxy may have multiple PLATE-IFUDESIGN designations if it has been observed multiple times. Please be cognizant of repeat observations when searching these catalogs.
Downloading the reduced spectra for one or more observations
The vast majority of users will want to download the final products of the Data Reduction Pipeline (DRP), either the datacube or RSS files. These are the final products of the 3d stage of the DRP as described by the data model, and a full description of how to download these files is provided in the Data Access page.
Choosing the file format: CUBE vs. RSS and LIN vs. LOG
There are four main output files per PLATE-IFUDESIGN identification of a MaNGA observation: row-stacked spectra (RSS) and datacubes (CUBE) files that are sampled either linearly (LIN) or log-linearly (LOG) in wavelength. The specific file that you should use for your project (LINRSS, LOGRSS, LINCUBE, or LOGCUBE) depends on your application and the format that may be required by any existing analysis software that you want to use. Some discussion to keep in mind when choosing which files to download is provided here. Note that the MaNGA DAP only analyzes the log-linearly binned data cubes (LOGCUBE files).
Downloading derived quantities; i.e. kinematics, emission-line properties, and spectral indices
Since DR15, we are providing the products of the Data Analysis Pipeline (DAP). The DAP currently only analyzes the datacubes produced by the DRP, not the RSS files. The DAP output is provided in the form of mapped values and model spectra as described the data model, and a full description of how to download these files is provided in the Data Access page.
Working with the data
There are specific procedural issues that you should keep in mind when working with the MaNGA data. Some of these will persist through the end of the survey (i.e., how to use the covariance matrices), whereas others may change given ongoing development of the DRP and DAP. We highlight specific issues in our discussion of working with MaNGA data, and the tutorials provide many working examples of accessing and visualizing MaNGA data.
Value Added Catalogs
Value Added Catalogs, or VACs, are data products contributed by SDSS-IV team members, based on SDSS-IV data. The MaNGA team has several of these catalogs now publicly available, listed here.
Frequently Asked Questions
We want you to use the MaNGA data for your science! If you have questions, we maintain a list of frequently asked questions, which may contain the answer.
If you are unable to find answers to your questions on that page or by consulting the tutorials, please email us at the SDSS helpdesk, and your question will be directed to an expert that can help you.
Quick reference to terminology
An comprehensive list of terminology used by SDSS can be found in the Survey Glossary. If you're unsure about the meaning of anything you see in the MaNGA documentation, this is your one-stop shop. We've collected of few of the primary terms here as a quick reference guide:
- The Catalog Archive Server is a searchable database that contains the measured parameters from all objects in the imaging survey and the spectroscopic survey. For MaNGA, the CAS provides search utilities for the DRPall and targeting catalogs.
- The MaNGA data analysis pipeline, the software package that processes the reduced data products provided by the MaNGA DRP to produce stellar and ionized-gas kinematics, nebular emission-line fluxes and equivalent widths, and a variety of spectral indices that characterize the galaxy continuum. The paper describing the DAP is listed among our technical papers here and briefly summarized here.
- The summary file created by the DAP that contains metadata (global information) from the MaNGA DAP, as well as useful global properties for each analyzed galaxy derived from the output maps files. See the description of the MaNGA Catalogs for a description of the DAPall file.
- A three-dimensional data array containing calibrated MaNGA imaging spectra for a single galaxy. The array consists of two spatial dimensions and a wavelength dimension encoding the spectrum at each point in the galaxy.
- The MaNGA data reduction pipeline, the software package that processes the raw MaNGA data into spectrophotometrically calibrated spectra, including an wavelength-dependent astrometric solution, in both datacube and RSS format. The paper describing the DRP is listed among our technical papers here and briefly summarized here.
- The summary file created by the DRP that contains metadata (global information) for all the MaNGA observations. This includes information for both galaxy and non-galaxy observations. For the galaxy observations, it includes salient global properties largely drawn from the NASA-Sloan Atlas.
- Integral-Field Unit (IFU)
- An assembly consisting of multiple optical fibers designed to collect spectra for a spatially extended object like a galaxy. Please see further description of the MaNGA instrument in the technical papers listed here, which is briefly summarized here. A general description of IFU spectroscopy is here.
- A unique identifier given to each galaxy observed by MaNGA, including the MaNGA ancillary programs. Any galaxy with a MaNGA-ID starting with '1-' has an entry in the NASA-Sloan Atlas.
- Marvin is a tool designed for overcoming the challenge of searching, accessing, and visualizing the MaNGA data. It consists of three components: a Web App, a Python package of Tools, and an API. Marvin combines these components to provide a seamless experience when using MaNGA Data.
- NASA-Sloan Atlas (NSA)
- The catalog of galaxy parameters, constructed from SDSS and GALEX observations, which was used for MaNGA target selection.
- Row-stacked spectra (RSS)
- A two-dimensional data array containing the calibrated spectra measured by individual MaNGA IFU fibers. The array consists of one dimension separating the observed fibers and one dimensions separating the observed wavelength channels. The on-sky position observed by each fiber in this array is a function of wavelength. Please see further description of the MaNGA data reduction pipeline in the list of technical papers listed here, which is briefly summarized here.
- DAP Map
- A short-hand for an image created by mapping an analysis quantity to the on-sky location of the spaxel from which it was derived.
- A unique identifier for a complete set of MaNGA observations for a given IFU on each plate. This is the most convenient identifier for finding a specific galaxy observation because it is included in the name of the fits file. Note: Each galaxy has a unique MaNGA-ID, but a galaxy may have multiple PLATE-IFUDESIGN designations if it has been observed multiple times.
- The Science Archive Server (found here), which serves the flat-files for SDSS.
- Spaxel (spectral pixel)
- A spatial element of the MaNGA datacube.
- The instrument used to obtain spectra of objects. MaNGA feeds into the two BOSS spectrographs. Please see further description of the MaNGA instrument in the technical papers listed here, which is briefly summarized here.
- Value Added Catalogs, listed here, are data products contributed by SDSS-IV team members, based on SDSS data.